This invention relates to machinery and, more particularly to mechanisms for transformation of force and speed parameters of progressive and rotary movements.
Lever mechanisms raising forces within one work cycle and transforming progressive and rotary movements are widely used (see Artobolevsky I. I., "Theory of Machines and Mechanisms", Moscow: "Science", 1975).
There exists the lever mechanism (Artobolevsky I. I., "The mechanisms in modern technique," Moscow: "Science", vol. 2, 1979, p. 15, example 872), consisting of an intermediate member with two end elements for progressive movements. Forces on the end element, speed of movement thereof and angular velocity of the intermediate member in such a mechanism are defined by following formulas: EQU P.sub.2 =P.sub.1 (sin .alpha..sub.1 /sin .alpha..sub.2)-.DELTA.P; EQU V.sub.2 =V.sub.1 (cos .alpha..sub.1 /cos .alpha..sub.2); EQU .omega.=V.sub.1 /(L sin .alpha..sub.1)=V.sub.2 /(L sin .alpha..sub.2);(1)
wherein: P.sub.2, P.sub.1 are forces on the end elements; V.sub.2, V.sub.1 are speeds thereof respectively; .alpha..sub.2 .alpha..sub.1 are angles between the plane containing the geometric axes of supporting surfaces of the end elements and directions of the end element movement; .DELTA.P is a reduction of force due to friction; and .omega. is a angular velocity of the intermediate member.
In such mechanisms the forces acting on the end elements may be balanced by torque acting on the intermediate member in accordance with formula: EQU M+P.sub.1 L sin .alpha..sub.1 +P.sub.2 L sin .alpha..sub.2 +.DELTA.=0;
where M is a torque on the intermediate member; .DELTA. is loss of force or torque due to friction, and other symbols are as defined above.
Such a mechanism can be used for mutual transformation of progressive and rotative movements with respective transformation of forces and torques.
Without taking into consideration loss due to friction, the force on one of the end elements may be unlimitedly great while the mechanism is in a certain position, whereas the force on the other end element or torque on the intermediate member is limited.
However sliding of loaded supporting surfaces causes intensive wear-and-tear, expenses to maintain reliability, and substantial reduction of the force capability of such mechanism. These deficiencies cause the use of antifriction materials, compound lubricating systems and ball or roller bearings. But the supporting surfaces continue to be the most vulnerable parts of such mechanisms.